[mchannon]

If you're going to make the space available, expect it to be filled to capacity during peak times. 500 sf is tiny and probably too small (your support staff onsite will take up a huge chunk of that, unless you're planning on having support staff offsite).

Unless I'm mistaken, most of Mountain View (and certainly Castro St) has free wifi internet through Google's agreement with the city. So that's neither a cost you need to worry about nor a service you can charge much of a premium for.

I'd expect at least an occupancy permit/business license. Probably not more than that if you're not doing things with food.

Instead of coworking, I'd consider using such a space to provide short-term rentals to startups, who will either go under or need more space weeks after they start using your space. The premium services you'd offer are having everything turnkey from internet to utilities to desks and chairs (and the ability for them to move out without it costing them an arm and a leg). I'd especially encourage you to consider taking stock options as part of (or instead of) the rent.

[SamReidHughes]

You're mistaken. Google's "free wifi" in Mountain View, particularly in downtown Mountain View, is unusable.